IAA quantification was carried out by GC-MS-SIM
based on Chen et al. (1988). HPLC fractions
correspondent to IAA were methylated with 1mL
etheric diazomethane for 5 min and reduced to
dryness at room temperature. The methylated
extracts were redissolved in 100 mL ethyl acetate
and analyzed in a gas chromatograph Hewlett-
Packards 6890 connected to a mass spectrometer
detector model 5973. The column used for separation
was an HP-1701 (30 m, I.D. 0.25 mm, I.T.
0.5 mm) and helium was the carrier gas, with a flux
of 4 mL/min. The injected volume for each sample
was 5 mL. Ions with a mass/charge (m=z) ratio
between 130 and 136 (endogenous IAA), and between 136 and 195 (internal standard) were
monitored. The endogenous IAA concentration was
obtained by comparing the peak areas of the
chromatograms extracted in m=z 130–136 and
136–195.